'Mouth-feeding' in monkeys after sensorimotor system lesions: an analysis based upon the Denny-Brown collection

Utilizing the Denny-Brown collection, we investigated an unusual feeding behavior exhibited by monkeys after sequential pre- and post-central gyrus lesions. The behavior involves ingestion of food by placing the lips directly over the food object, i.e., 'mouth-feeding.' Interestingly, this behavior persists long after recovery of the ability to hand-feed. In all of the cases within the collection and in descriptions of mouth-feeding found in the literature, mouth-feeding occurs only after bilateral lesions. We suggest that the co-existence of mouth- and hand-feeding behavior in animals with pre- and post-central gyrus lesions results partly from the sparing of corticospinal projections arising outside these gyri, e.g., the cingulate region, thereby preserving to a certain extent discrete use of the forelimbs.